As the display technology is improving day by day, consumers demand higher and higher image quality of displaying systems such as liquid crystal displays, smart TVs, and a tablet PCs. Among many approaches, enhancing image contrast is a way to improve the image quality.
To make images displayed on a display more colorful, image data of one frame are usually analyzed by statistics and processed to be a histogram. As shown in FIG. 1, the numbers of gray values of R, G, and B components falling into respective intervals are counted for all the pixels in that frame. Next, a transformation curve is created as shown in FIG. 2. The use of the transformation curve is to increase a distributed range of gray values to be presented or displayed on a screen when the number of these gray values falling into some particular interval is large. After the transformation, each gray value in every pixel for that frame will map to another value via a one-to-one mapping and then output to a display panel.
However, the afore-described approach is to pool the gray values of red (R) component, green (G) component, and blue (B) component of one image frame all together and then create the transformation curve. For some particular frame that has great color distribution difference, pooling the gray values of R, G, and B components all together will homogenize the overall distribution. This makes the ratio of input to output become almost 1:1, thereby unable to enhance the image contrast effectively. As shown in FIGS. 3A to 3C, these figures respectively show the quantity distribution of the gray values of R, G, and B components in respective intervals for a single image frame. FIG. 4A illustrates that the gray values of R, G, and B components of this frame are pooled all together. It can be known that the overall distribution is much unvaried or even such that the slop of transformation curve approximately becomes 1, as shown in FIG. 4B. That is, the input value is almost equal to the output value, thereby unable to improve the contrast effectively.
Therefore, there is a need to provide a novel method capable of enhancing the image contrast, for avoiding the above described drawbacks of conventional skills.